中国科学院数学与系统科学研究院期刊网
A Formula of Euler Characteristic of Two Dimensional Compact Riemann Manifolds of Nonpositive Curvature
Ming YANG
Acta Mathematica Sinica, Chinese Series . 1999, (6): 0 -0+0 .  DOI: 10.12386/A1999sxxb0137